It is well known that it is desirable to provide hospitals, nursing homes, or the like, with a cleaning machine which not only picks up dust and dirt but also does not redistribute dirt particles and undesired bacteria back into the room being cleaned to thereby contaminate the air therein. Thus, sanitary conditions in a hospital are of paramount consideration. Heretofore, a number of vacuum cleaning machines and methods have been used in hospitals or the like for removing minute dirt and dust particles from air streams, however, these machines and methods have resulted in something less than the order of 99% of arresting of these particles in the filter bag. In the alternative, if the desirable trapping of particles is achieved, the air flow rate within the cleaning machine was so low as to be impractical. One arrangement has been proposed in U.S. Pat. No. 3,971,643 to Hufton, having an air-impervious outer bag, and a conventional inner paper dust bag. The outer dust bag is provided with an opening in which a rectangular-shaped filter is removably inserted. This arrangement does not have the filtering capabilities of the present design besides being more costly and complicated to manufacture.
The present invention relates to a filter dust bag for a vacuum cleaner apparatus which effectively removes minute particles of dust and dirt from a moving stream of air.
It is an object of the present invention to provide a multi-layer filter dust bag that removes minute particles from a high velocity air stream.
It is another object of the present invention to provide an apparatus including a dust bag for efficiently picking up dirt and dust without discharging bacteria or other undesired matter into the air of a room that has been cleaned.
It is a further object of the present invention to provide a multi-layered filter dust bag having a fibrous intermediate air-pervious filter element.
It is still another object of the present invention having spaced inner and outer compartments of the filter bag that are constituted of air-pervious material of the same or different permeability rates.
It is a further object of the present invention to provide a multi-layer filter dust bag that can be substituted for the conventional filter bag currently being used in upright vacuum cleaners for cleaning hospitals or the like.
It is still another object of the present invention to provide an inner multi-layer filter bag for upright vacuum cleaners that insures substantially total filtration of the discharged air through the inner filter bag.
It is yet another object of the present invention in which the dust collecting and filtering elements of the bag are installed in the vacuum cleaning apparatus as a single unit and removed simultaneously.
A further object of the present invention is to provide a multi-layered filter dust bag which is safely contained within an air-pervious outer bag having a closable access opening. The dust bag is disposable after the dirt collection capacity has been reached.
Another object of the present invention is to provide a filter dust bag that results in the reduction of the noise level in the vacuum cleaning apparatus.